Valve seal and device for dispensing a fluid product while being provided with a seal of this type

ABSTRACT

The invention relates to a valve seal for an aerosol dispenser serving to dispense a fluid product. The invention is characterized in that said seal contains an elastomer based on ethylene propylene (EP) and/or or on ethylene propylene diene (EPDM), and contains a mineral filler based on quartz (SiO 2 ) and on kaolinite (Al 4 [( 0 H) 8 Si 4 O 10 ]).

This present invention concerns a valve seal and a device for thedispensing of a fluid product that includes such a seal.

One is familiar, in particular for the dispensing of pharmaceuticalproducts, with the use of devices of the aerosol type, in which theproduct is dispensed by means of a propellant gas. For ecologicalreasons, the propellants used previously, which were generallyCFC-based, have been replaced by other propellant gases, and inparticular propellant gases of the HFC-134a or HFC-227 type. It turnedout that this change of the propellant gas gave rise to various stresseson the seals, whether regarding the sealing effectiveness of the saidseal, or regarding extractible substances, when the said seal was incontact with these new propellant gases. It so happened that the sealmaterials normally used in aerosol valves in conjunction with CFC gasescould not be applied easily to the new propellant gases. Variousmaterials were therefore developed for use with these HFC gases. Ofthese materials, ethylene propylene (EP) and ethylene propylene dienemonomer (EPDM) turned out to be appropriate materials. Another problemthat arises with HFC gases, is that when they are used with a latentsolvent, such as ethanol for example, there is a tendency for thealcohol, which is less soluble in the liquid phase of the HCFs, toseparate out, thus exposing the seals to a higher concentration ofalcohol than has been the case previously with the CFC gases. Ethylenepropylene and ethylene propylene diene monomer have also proven to beappropriate materials for solving this problem.

Document EP-0 969 069 describes a valve seal that is intended for afluid product dispenser that includes EPDM as well as a mineral fillerthat includes magnesium silicate and/or Kaolin. The purpose of thesemineral fillers is to improve the properties of the seal, and inparticular the aspects concerning its sealing properties.

The purpose of this present invention is to supply a valve seal thatincludes a different mineral filler, in order to obtain goodcharacteristics for the seal, in particular those aspects concerning theeffectiveness of its sealing properties, its elastic properties, and themanufacturing process of the seal.

Another objective of this present invention is to provide such a valveseal with improved sliding properties and with a reduced extractiblesubstances leeching rate.

A further objective of this present product is to supply such a valveseal which is simpler and less costly to manufacture than the previouslyknown valve seals.

The subject of this present invention is therefore a valve seal that isintended for a fluid product aerosol dispenser, characterised in thatthe said seal includes an elastomer which is based upon ethylenepropylene (EP) and/or ethylene propylene diene monomer (EPDM), and amineral filler that is based upon quartz (SiO₂) and Kaolinite (Al₄[(OH)₈Si₄O₁₀]).

Advantageously, the mineralogical composition of the mineral fillerincludes between 65% and 95%, preferably about 80%, of quartz, andbetween 5% and 35% preferably about 20%, of Kaolinite.

Advantageously, the chemical composition of the mineral filler includesbetween 3% and 15%, preferably about 8%, of Al₂O₃, and between 75% and95%, preferably about 87%, of SiO₂ .

Advantageously, the mineral filler has a pH greater than 6, preferablybetween about 7 and 8.

Again advantageously, the mineral filler has an average particle size ofbetween 1.5 and 4 microns, preferably about 2.2 microns.

Advantageously also, the said seal, before its assembly into a fluidproduct aerosol dispenser, is subjected to a surface chlorinationtreatment.

Advantageously again, the said seal is immersed in a solution containingwater, hydrochloric acid and bleach.

Another objective of this present invention is a measuring-out valve fora fluid product aerosol dispenser that includes at least a valve seal asdescribed above.

This present invention also has as its objective a fluid product aerosoldispenser that includes a reservoir containing a fluid product and apropellant gas, and a valve, preferably a measuring-out valve, mountedon the said reservoir, where the said valve includes at least a valveseal as described above.

Advantageously, the said valve includes a valve element sliding in avalve body with the interposition of a valve seal, where the said valveseal is made as described above.

Advantageously, the said propellant gas includes HFC-134a gas and/or ofthe HFC-227 gas.

Advantageously, the reservoir also contains alcohol, ethanol inparticular.

Another objective of this present invention is a manufacturing processfor a valve seal intended for a fluid product aerosol dispenser,characterised in that the process includes the following stages:

-   creation of a seal that includes an elastomer based upon ethylene    propylene (EP) and/or ethylene propylene diene monomer (EPDM), and a    mineral filler based upon quartz (SiO₂) and kaolinite    (Al₄[(OH)₈Si₄O₁₀)], and-   submission of this seal to a surface chlorination treatment.

Advantageously, the said surface chlorination treatment includesimmersing the seal in a solution containing water, hydrochloric acid andbleach.

The mineral filler of this present invention has a structure which isboth granular and lamellar. This results in improving the elasticproperties of the seal, improving the effectiveness of the sealingproperties of the seal, and also simplifies the manufacturing process ofthe said seal. A material that is particularly suitable to be used inaccordance with this present invention is Sillitin, which is a naturalmixture of quartz and kaolinite. This material has never been used inthe manufacture of valve seals, in particular of the type of dynamicvalve seal in which the valve element slides.

The following two tables contain a comparison between Sillitin andkaolin, firstly regarding the aspects concerning their chemicalformulae, and secondly the aspects concerning the characteristics ofthese products. 1) Chemical formulae Filler Formula Sillitin (Naturalmixture of quartz Al₄[(OH)₈Si₄O₁₀]—Si0₂ (80%) and kaolinite (20%))Kaolin Al₂0₃—2SiO₂

2) Characteristics Characteristics Sillitin Kaolin Chemical analysisAl₂0₃ (%) 8 44 SiO₂ (%) 87 52 Other (%) 5 4 pH 7-8 5-6 Average size ofthe 2.2 1.4 particles (μm)

Referring in particular to the table concerning the characteristics, itcan be seen that Sillitin contains much less Al₂O₃ and much more SiO₂ inrelation to Kaolin. The granular and lamellar structure of Sillitinresults in improving the effectiveness of the seal in relation to a sealwith the same elastomer, such as EP or EPDM for example, but a mineralfiller composed of Kaolin. The neutral pH can limit the interactionsbetween the seal and the active ingredient contained in the fluidproduct to be dispensed.

It therefore emerges that a seal that includes EP and/or EPDM, and amineral filler that includes Sillitin, is particularly suitable for usewith HFC gases. It is also particularly suitable to be used with HFCgases in the presence of alcohol, and ethanol in particular.

This present invention therefore results in improving the seal describedin document EP-0 969 069.

According to one advantageous method of implementation, the seal canalso be subjected to a surface chlorination treatment. This treatment isused in particular to reduce the electrostatic character of the seal.The properties of the seal, in particular its sliding quality, aretherefore ameliorated. This treatment is also used to reduce theleeching of extractible substances, and therefore limits the risk ofinteraction with the active product. Advantageously, this surfacetreatment can be effected by immersing the seal in a solution containingwater, hydrochloric acid and bleach. This leads to the formation ofchlorine which attaches itself to the surface of the seal.

Although this present invention has been described with reference to oneimplementation example, namely the use of Sillitin, it is intended thatthe invention should not be limited to this single implementationmethod, but that, on the contrary, a professional engineer should beable to effect appropriate changes without moving outside the context ofthe invention as described by the following claims.

1. A valve seal intended for a fluid product aerosol dispenser,characterised in that the said seal includes an elastomer based uponethylene propylene (EP) and/or ethylene propylene diene monomer (EPDM),and a mineral filler based upon quartz (SiO₂) and Kaolinite(Al₄[(OH)₈Si4O₁₀]).
 2. A seal according to claim 1, in which themineralogical composition of the mineral filler includes between 65% and95%, preferably 80%, of quartz, and between 5% and 35%, preferably about20%, of Kaolinite.
 3. A seal according to claim 1, in which the chemicalcomposition of the mineral filler includes between 3% and 15%,preferably about 8%, of Al₂O₃, and between 75% and 95%, preferably about87%, of SiO₂.
 4. A seal according to claim 1, in which the mineralfiller has a pH greater than 6, preferably between about 7 and
 8. 5. Aseal according to claim 1, in which the mineral filler has an averageparticle size of between 1.5 and 4 microns, preferably about 2.2microns.
 6. A seal according to claim 1, in which the said seal, beforeits assembly into a fluid product aerosol dispenser, is subjected to asurface chlorination treatment.
 7. A seal according to claim 6, in whichthe said seal is immersed in a solution containing water, hydrochloricacid and bleach.
 8. A measuring-out valve for a fluid product aerosoldispenser, characterised in that it includes at least a valve sealaccording to claim
 1. 9. A dispenser for dispensing a fluid product,that includes a reservoir containing a fluid product and a propellantgas, and a valve, preferably a measuring-out valve, mounted on the saidreservoir, characterised in that the said valve includes at least avalve seal according to claim
 1. 10. A dispenser according to claim 9,in which the said valve includes a valve element sliding in a valve bodywith the interposition of the valve seal.
 11. A dispenser according toclaim 9, in which the said propellant gas includes HFC-134a gas and/orHFC-227 gas.
 12. A dispenser according to claim 9, in which thereservoir also contains alcohol, and ethanol in particular.
 13. Amanufacturing process for a valve seal intended for a fluid productaerosol dispenser, characterised in that the process includes thefollowing stages: creation of a seal that includes an elastomer basedupon ethylene propylene (EP) and/or ethylene propylene diene monomer(EPDM), and a mineral filler based upon quartz (SiO₂) and kaolinite(Al₄[(OH)₈Si₄O₁₀)]; submission of this seal to a surface chlorinationtreatment.
 14. A process according to claim 13, in which the saidsurface chlorination treatment includes immersing the seal in a solutioncontaining water, hydrochloric acid and bleach.